What was Of Grammatology about? When Madeleine, the heroine of Jeffrey Eugenides’s campus novel The Marriage Plot, asks a young theory-head this question, she is immediately set straight: ‘If it was “about” anything, then it was about the need to stop thinking of books as being about things.’

That’s not so far off. In all three books, Derrida’s argument was that Western thought from Plato to Rousseau to Lévi-Strauss had been hopelessly entangled in the illusion that language might provide us with access to a reality beyond language, beyond metaphor: an unmediated experience of truth and being which he called ‘presence’. Even Heidegger, a radical critic of metaphysics, had failed to escape its snares. This illusion, according to Derrida, was the corollary of a long history of ‘logocentrism’: a privileging of the spoken word as the repository of ‘presence’, at the expense of writing, which had been denigrated as a ‘dangerous supplement’, alienated from the voice, secondary, parasitic, even deceitful.